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Joint borrower sole proprietor mortgages (JBSP): how family can help you buy
A joint borrower sole proprietor (JBSP) mortgage lets a family member add their income to your mortgage application without owning any of the home. They're named on the mortgage and share responsibility for the repayments, but only you are on the title deeds. It can help you borrow more than you could alone, but the helper takes on real risk.
Lender criteria vary and change often. This guide covers the typical rules, not the rules for any one lender.
Who owns the home
Only you
The helper is on the mortgage but not on the title deeds.
Who owes the debt
Everyone
Each borrower is liable for the whole mortgage, not just a share.
Helper's age
Often 70–85
Common maximum age at the end of the term, which can shorten the term.
Borrowers
Up to 4
A usual limit, and at least one must be the owner who lives in the home.
What is a joint borrower sole proprietor mortgage?
With a standard joint mortgage, everyone who borrows also owns the property. A JBSP mortgage splits those two roles. Parents, or sometimes other relatives, join as borrowers so the lender can count their income. You stay the sole proprietor, the only legal owner.
You may also see it called a JBSP mortgage, a joint mortgage sole proprietor, an income booster or a family boost mortgage. The idea is the same.
Who is on the mortgage and who is on the title
A parent helping a first-time buyer
Who does a JBSP mortgage suit?
It's most useful when you can afford the monthly payments in practice, but your income alone doesn't support the loan size you need.
First-time buyer helped by parents
The most common use
Your parents' income tops up yours so you can borrow enough to buy. Read our £5k deposit guide for other ways in.
Parent helped by adult children
Later-life buyers
After divorce or retirement, a parent may need their children's income to buy. The children's ages can allow a longer term.
Career starters on lower pay
Income expected to rise
Trainees and graduates on starting salaries can use family support now, then aim to remortgage alone once their pay grows.
Helper already owns a home
Stamp duty can be lower
If a homeowning parent bought jointly with you, the 5% additional property surcharge could apply. As a JBSP helper they're not on the title, so it usually wouldn't.
How stamp duty works with JBSP
In England and Northern Ireland, stamp duty is based on the people buying the property, not the people borrowing. Because the helper isn't a purchaser, their own home usually doesn't trigger the 5% surcharge on additional dwellings. If you're a first-time buyer, you may still qualify for first-time buyer relief.
There are exceptions. HMRC treats married couples and civil partners as one unit, so if your spouse or civil partner owns another home, the surcharge can still apply. The helper must also have no beneficial interest in the property, such as a right to a share of the sale proceeds. Scotland and Wales have their own taxes and rules.
We are not tax advisers and this is not tax advice. This stamp duty information is a general summary based on the rules published at the time of writing, and we make no warranty about the tax you will pay. Your solicitor or conveyancer will confirm the amount due. Speak to a qualified tax adviser or accountant about your own circumstances.
How do lenders assess a JBSP mortgage?
The lender assesses every borrower as if they were a normal applicant, then decides whether the combined household can afford the loan. Criteria vary a lot between lenders, and not every lender offers JBSP, so these are typical checks rather than fixed rules.
What lenders typically look at
- Combined income
- Incomes are added together, though some lenders count a helper's income differently or cap the total multiple.
- Helper's age and term
- Many lenders set a maximum age at the end of the term, commonly between 70 and 85, or use retirement age. An older helper can mean a shorter term and higher payments.
- Retirement income
- If the term runs past the helper's retirement, lenders usually want to see pension income that keeps it affordable.
- The helper's own commitments
- Their mortgage, loans and credit cards come off their income first, which can leave less to add than you expect.
- Relationship
- Many lenders want helpers to be close family, such as parents or grandparents. A few don't restrict who can help.
- Number of borrowers
- Up to four applicants is a common limit, and some lenders cap how many can be non-occupiers.
- Credit history
- Every borrower goes through credit checks, so a helper's poor credit can affect the whole application.
- Legal advice
- Lenders commonly insist that helpers take independent legal advice from a solicitor before completion.
JBSP vs guarantor mortgage, gifted deposit and joint mortgage
There are several ways family can help. The right one depends on whether they can offer income, savings or cash, and how much risk they're prepared to take.
| Option | How family helps | Helper on the title? | Helper's risk |
|---|---|---|---|
| Joint borrower sole proprietor | Adds their income to the mortgage | No | Liable for the whole debt, with no share of the home |
| Joint mortgage | Borrows and buys with you | Yes | Liable for the whole debt, but owns a share of the home |
| Guarantor mortgage | Promises to cover payments you miss, sometimes backed by their savings or home | No | Pays if you don't; now offered by few lenders |
| Gifted deposit | Gives you cash towards the deposit | No | The money is gone, but there's no ongoing liability |
| Family springboard or deposit-backed mortgage | Places savings, often 10% of the price, in a linked account for a set period | No | Savings are locked away and at risk if you fall into arrears |
Families sometimes combine options, for example a gifted deposit alongside a JBSP mortgage.
What are the risks for the helper?
Helpers often think of JBSP as lending their name. Legally, it's much more than that.
- Jointly and severally liable: if payments are missed, the lender can pursue any borrower for the full amount owed, not a share.
- Credit file: the mortgage appears on their credit report, and missed payments will harm their score as well as yours.
- Future borrowing: other lenders will count the mortgage as a commitment, which can limit a helper's own remortgage or move.
- No ownership: they have no share of the home or its value, and no say if you sell.
- Family pressure: relationships, divorce or a fall-out can make the arrangement hard to unwind.
Before a helper signs
Helpers should take independent legal advice from a solicitor who isn't acting for the buyer, and most lenders require it. It's also sensible for helpers to get separate mortgage advice about how the commitment affects their own plans, and for the family to agree in writing what happens if circumstances change.
Are JBSP mortgage rates higher?
Not necessarily. Where a lender offers JBSP, rates are often in line with its standard residential products at the same loan-to-value. The bigger difference is choice: fewer lenders accept JBSP, so there are fewer deals to compare, and some specialist or building society options may price differently.
Your deposit size, credit history and the lender you're matched with will shape your rate more than the JBSP structure itself. For the wider picture, see our current UK mortgage rates update.
Can you remove the helper later?
Yes, usually. JBSP is often a stepping stone. When your income can support the mortgage alone, you can apply to take the helper off.
The most common route is a remortgage into your sole name, with a new lender or your existing one. You'll need to pass affordability on your own income. Some lenders allow a borrower to be removed at the end of a fixed rate, and a few build this into the product. Time any change around early repayment charges.
A helper can't simply ask to come off the mortgage. The lender must agree, and it will want to see that the remaining borrower can afford the payments.
How to get a JBSP mortgage: step by step
- Talk it through as a familyAgree who will help, for how long, and what happens if you can't pay or want to sell.
- Check which lenders fitAges, relationships, number of borrowers and income all narrow the list. A broker can match you before you apply.
- Get an agreement in principleThis involves credit checks on everyone, so gather payslips, bank statements and details of the helper's own commitments first.
- Make an offer and applyThe lender assesses all borrowers, values the property and underwrites the case.
- Helpers take legal adviceTheir solicitor explains the liability and confirms this to the lender, usually with a signed certificate.
- Complete and plan your exitOnly you go on the title. Review each time your deal ends to see if you can take the helper off.
Frequently asked questions
Can a friend be a joint borrower?
Most lenders want a close family member, such as a parent, grandparent or sibling. A small number have no relationship restriction, so it's worth asking a broker.
Can the helper live in the property?
Some lenders allow it, but many JBSP helpers don't live there. If they do, the lender will usually ask them to sign a form confirming they have no ownership rights.
Can I use JBSP to remortgage?
Often, yes. Some lenders accept JBSP for remortgages and product switches, for example to add a family member when you couldn't pass affordability alone.
Does being a joint borrower affect my own mortgage?
It can. The full JBSP mortgage payment usually counts against your affordability when you apply for your own mortgage, and it shows on your credit file.
Do I need a joint borrower mortgage specialist?
You don't have to use one, but JBSP criteria differ widely and not all lenders offer it. An experienced joint borrower mortgage broker can find lenders whose age, income and relationship rules fit your family first time.
How we can help
A JBSP mortgage works best when the lender's rules fit your family from the start. Quick Mortgages is a whole-of-market broker, not tied to any lender, with a panel of more than 110 lenders including building societies and specialist lenders. There are no broker fees, and we help buyers across the UK from our Birmingham office.
Buying your first home? See our first-time buyer mortgages. Ready to take a helper off your mortgage? Look at remortgaging.
Sources
- HMRC, Stamp Duty Land Tax Manual SDLTM09764: higher rates for additional dwellings, joint purchasers and beneficial interest
- GOV.UK, Stamp Duty Land Tax: higher rates for additional properties (5% surcharge)
- Skipton Building Society for Intermediaries, Income Booster criteria
- Darlington Building Society Intermediaries, joint borrower sole proprietor criteria
- Barclays, Family Springboard Mortgage product information
- Tembo, age limits for joint borrower sole proprietor mortgages (updated April 2026)
Correct on 17 September 2026 and may change.
Disclaimer:
This article is for general guidance purposes only and does not constitute legal, financial, or professional advice. Mortgage products and their terms can vary, and it is important to seek advice from a qualified, regulated professional who can assess your individual circumstances. Please ensure you consider your unique needs before making any financial decisions.
While every effort is made to ensure that the information provided on this blog is accurate and up-to-date, we do not guarantee its completeness or accuracy. The mortgage market can change rapidly, and the information on this blog may become outdated. We recommend verifying any information before acting on it and seeking tailored advice.
THINK CAREFULLY BEFORE SECURING OTHER DEBTS AGAINST YOUR HOME. YOUR HOME OR PROPERTY MAY BE REPOSSESSED IF YOU DO NOT KEEP UP REPAYMENTS ON A MORTGAGE OR ANY OTHER DEBT SECURED ON IT.
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